Control mechanism



y 1962 R. H. KIESSLING 3,045,503

CONTROL MECHANISM Filed May 28, 1959 2 Sheets-Sheet 1 INVENTOR. RUDOLF H. KIESSLING July 24, 1962 Filed May 28, 1959 R. H. KIESSLING CONTROL MECHANISM Fig-4 2 Sheets-Sheet 2 INVENTOR. Rz/DOLF H. K/ESsL/NG 3,045,563 CONTRUL MECHANISM Rudolf H. Kiessling, Milwaukee, Wis, assignor to Square D Company, Park Ridge, ill., a corporation of Michigan Filed May 28, 1959, Ser. No. 816,570 6 Claims. (til. 74-395) The present invention relates to an actuating mechanism for electrical switches and more specifically to a Vernier adjustment for limit switch arms.

The invention finds use in those types of electrical switches commonly known as limit switches and especially limit switches which have an arm mounted on an operating shaft with the arm pivotally movable to at least partially rotate the shaft to operate the switch. Switches of this type are finding many uses in the machine tool and other industries wherein movement of one part relative to another part of the machine tool operates the switch. Generally the switches must be set so that the switch is operated precisely at a desired relative position between the relatively movable parts. In order to perform this operation, and especially in the machine tool industry, the switch must be operated and must be adjustable for operation within close tolerances. In the past this has meant that the position of the switch on one of the relatively movable parts had to be maintained within those close tolerances. Such tolerances or close positioning was obtained through the bolts or screws fastening the switch to the suppoorting part, or trying to clamp the arm on the operating shaft of the switch at an exact position.

It is well recognized that such adjustments are very diflioult to make, if not entirely impossible, and that if the arm slips on the shaft, or the mounting screws become slightly loose the adjustment is completely lost.

One of the objects of the present invention is to overcome the aforementioned problems and others.

Another object of the present invention is to provide an electrical switch actuating arm with a vernier adjustment.

A further object of the invention is to provide a combined Vernier adjustment and limit switch arm which may be easily mounted on existing limit switches in place of the old actuating arms to make the limit switch easily adjust-able.

Other objects and a fuller understanding of this invention may be had by referring to the following description and claims, taken in conjunction with the accompanying drawings in which:

FIGURE 1 is a perspective view of a limit switch incorporating the features of the invention.

FIGURE 2 is a cross sectional view taken approximately along the line 22 of FIGURE 1, to more fully illustrate the structure of the Vernier adjustment and actuating arm on the operating shaft of the switch.

FIGURE 3 is a sectional view taken approximately along the line 33 of FIGURE 2 to better illustrate the gears used in the Vernier adjustment.

FIGURE 4 is a sectional view similar to FIGURE 2 but showing a modification of the invention.

The description, drawings, and claims jointly set forth one or more embodiments of the present invention and the present contribution to the art of providing easily adjusted electrical switches which will operate within very close tolerances.

For purposes of exemplification and not of limitation, the combined Vernier adjustment and actuating arm is illustrated in cooperation with an electrical switch of the type commonly known as a machine tool limit switch, for example, the limit switch illustrated in Patent No. 2,822,439 issued on February 4, 1958, to C. A. Schaefer et al. These switches comprise an electric limit switch $345,503 Patented July 24, 1962 ice 16 having an actuating arm 11 provided at one end with a hub 12 mounted on an operating shaft 13 and terminating at the other end in a roller 14. Limit switch 10 is operated from its on to its oif position or vice versa by pivotal movement of the actuating arm 11 and partial rotation of operating shaft 13 from one position, indicated in solid lines in FIGURE 1, to another position, indicated in dash-dot lines 15 in FIGURE 1. [In FIG- URE 1 this angular or pivotal movement of actuating arm 11 to operate switch 10 has been greatly exaggerated.

As illustrated in FIGURE 2, operating shaft 13 comprises a rotatable operating shaft 16 and a screw 17 threaded axially into the end thereof. Rotatable operating shaft 16 is provided with a shoulder 18 and hub 12 is positioned between the shoulder 18 and the head 17 of screw 17.

Hub 12 comprises a flange gear 20, an end portion 21 of arm 11 and a dial 22. Flange gear 20 is somewhat cupshaped and has a center opening 23 receiving rotatable operating shaft 16 when flange gear 20 is abutted against shoulder 18 and fixed to shaft 16 for movement therewith. Flange gear 2i} also has a peripheral flange 24 provided with X number of internal gear teeth 25 disposed concentric about the axis of .at least partially rotatable operating shaft 16.

End portion 21 of arm 11 abuts peripheral flange 24 and is provided with an opening with X plus Y or X minus Y internal gear teeth 26, also disposed concentrically about the axis of rotatable operating shaft 16. In this instance the gear teeth 25 and 26 have the same base circle diameter or pitch diameter. In the description the letter X represents any desired number of teeth and the letter Y represents any constant, for example, one, two, or three, so that end portion 21 will have a different nurnber of teeth than peripheral flange 24.

Dial 22 is journaled on rotatable operating shaft '16 for rotation relative thereto and has an eccentric portion 27 at least partially encircling rotatable operating shaft 16 and positioned within end portion 21 and peripheral flange 24. Eccentric portion 27 supports an external ring gear 28 which has external teeth 29 simultaneously engageable with at least some of the gear teeth 25 and some of the gear teeth 26. For example, when flange gear 20 is provided with fifteen gear teeth 25, end portion 21 is provided with sixteen gear teeth 26 and external ring gear 28 is provided with fourteen gear teeth 29, some of the gear teeth 29 simultaneously engage and forcibly align some of the gear teeth -25 with some of the gear teeth 26 to effect an adjustment of arm .11 about shaft 16.

In operation, limit switch 10 is simply mounted in a position whereby an object, which is to cause operation of the switch, will engage roller 14 to pivot actuating arm 11, and thereby at least partially rotate rotatable operating shaft 16 to effect operation of limit switch 10. The exact angular positioning of actuating arm 11 may easily be adjusted by simply loosening screw 17 and thereafter rotating dial 22 relative to rotatable opera-ting shaft 16 and limit switch 10 until actuating arm 11 has attained the desired angular position relative to shaft 16. Rotation of dial 22 effects a revolving movement of external ring gear 28, and thus differential rotary movement of end por tion 21 relative to peripheral flange 24.

After dial 22 has been rotated a sufiicient number of times, or a suflicient part of a single turn, to position actuating arm 11 relative to the limit switch operating shaft 16, screw 17 is again tightened to lock dial 22 against unintentional rotation.

In the modification of FIGURE 4, operating shaft 113 comprises a rotatable operating shaft 116 and a screw 117 having a head 117' and threaded axially into the end thereof. Rotatable operating shaft 116 is provided with a 3 shoulder 118 and hub 1'2 is positioned between shoulder 118 and the head 117. A spring washer 119 has also been placed between head 117 and hub 12 on shaft 116.

Hub 12 comprises a stationary gear 120, a movable gear 121 of actuating arm 11 and a dial 122. Stationary gear 120 has a center opening 123 receiving rotatable operating shaft 116 when stationary gear 120 is abutted against shoulder 1 18 and secured to shaft 116 for movement therewith. Stationary gear 120 is secured to shaft 116 for movement therewith by suitable means, for example brazing metal 140. Stationary gear 120 also has frustroconical shaped flange 124 on the side 120' thereof facing dial 122. This flange is provided with an external frustroconical bearing surface 124 and internal gear teeth 125.

Movable gear 121 is provided with a frustro-conical internal bearing surface 121' bearinged against bearing surface 124' and gear teeth 126 aligned for cooperative action with gear teeth 1125. The teeth 126 extend from the apex end of internal bearing surface 121', part way through movable gear 121 and to a wall 21a which has an internal diameter less than the root diameter of teeth 126.

Dial 122 is journaled in wall 21a and on rotatable operating shaft 116 for rotation relative thereto and has an integral eccentric portion 127 at least partially encircling rotatable operating shaft 116 and positioned within movable gear 121 and peripheral flange 124. A linking gear 128 is mounted on eccentric portion 127 and has external teeth 129 simultaneously engageable with at least some of the internal gear teeth 125 and 126. Dial 122 has shoulders 130 and 131 axially spaced apart and separated by the portion of dial 122 which is bearinged in wall 210 whereby shoulder 130 is on one side of wall 21a and shoulder 131 rests against wall 21a and the outer surface of movable gear 121. Linking gear 128 has a length less than the distance between wall 21a and side 120' and extends therebetween, or between shoulder 130 and side or face 120. As further illustrated, the dial 122 may be provided with a recess 13 2 to receive head 117', spring washer 119 and a locking ring 133 which extends around the free end of shaft 116 and prevents dial 122 from falling off shaft 116 if screw 117 is removed. Spring washer 119 urges dial 122 and movable gear 121 towards stationary gear 120 even when screw 117 is not completely tight.

It is apparent that operation of the device of FIGURE 4 is substantially the same as that of the other figures and therefore will not be fully described herein.

Although this invention has been described in its preferred form with a certain degree of particularity, it is understood that the present disclosure of the preferred form has been made only by way of example and that numerous changes in the details of construction and the combination and arrangement of parts may be resorted to without departing from the spirit and the scope of the invention as hereinafter claimed.

What is claimed is:

1. In a switch actuating arm and shaft device for operating an electrical switch upon rotation of the shaft by pivotal movement of the arm, the provision of said arm having an end portion provided with a plurality of internal gear teeth encircling said shaft, a first gear secured to and encircling said shaft and provided with a number of internal gear teeth different from and coaxially aligned with the gear teeth on said end portion, an adjusting hub rotatable on said shaft having a portion for positioning the arm on the shaft, and an eccentric portion extending within the gear teeth on said first gear and said end portion, and a second gear surrounding said eccentric portion and revolvable about said shaft to cause movement of said arm relative to said first gear upon rotation of said hub.

2. The structure of claim 1 including screw means threaded into said shaft and engageable with said hub to lock said hub to said shaft, thereby to lock said arm in an angular position relative to said shaft.

3. In a switch actuating arm and shaft device for operating an electrical switch upon rotation of the shaft by pivotal movement of the arm, the provision of said arm having an end portion provided with a plurality of internal gear teeth encircling said shaft, a first ring gear secured to and encircling said shaft and provided with a peripheral flange having internal gear teeth of different number than and coaxially aligned with the gear teeth on said end portion, a dial rotatable on said shaft and having a portion engaging the gear teeth on the arm for positioning the arm relative to the shaft and an eccentric portion within said flange and end portion, a second ring gear surrounding said eccentric portion and revolvable about said shaft and having external gear teeth simultaneously engaging the internal gear teeth of the arm and first ring gear to cause differential movement of said arm relative to said first ring gear upon rotation of said dial, and screw means threaded into said shaft and engageable with said dial to retard movement of said dial relative to said shaft, thereby to lock said arm in an angular position relative to said shaft.

4. The structure of claim 3 wherein said arm and said first ring gear have different total numbers of gear teeth thereon and wherein the gear teeth on said arm and said first ring gear have at least approximately the same base circle diameter.

5. In a switch actuating arm and shaft device for operating an electrical switch upon rotation of the shaft by pivotal movement of the arm, the provision of said arm having an end portion provided with an opening defining a frustro conical shaped bearing surface and a cylindrical bearing surface spaced apart and a plurality of internal gear teeth disposed between said surfaces in said opening, first gear means secured to and encircling said shaft and provided with a flange having an external frustro conical surface in bearing engagement with the bearing surface on said arm and having internal gear teeth of different number than and coaxially aligned with the gear teeth on said end portion, a dial having an eccentric portion extending within said flange and end portion, and a second gear means having external gear teeth in engagement with the gear teeth of the arm and first gear means and revolvable by said eccentric portion upon rotation of said dial relative to said first gear means to cause movement of said arm relative to said first gear means.

6. The structure of claim 5 including means co-engageable with the shaft and dial to lock the dial to the first gear means, thereby to lock said arm in an angular position relative to said shaft.

References Cited in the file of this patent UNITED STATES PATENTS 2,370,992 Perry et al. Mar. 6, 1945 2,404,116 Wolowicz et a1 July 16, 1946 2,667,076 Pavre Jan. 26, 1954 2,790,332 Caster et al Apr. 30, 1957 FOREIGN PATENTS 82,334 Norway Aug. 31, 1953 

